CAT661 Datasheet, PDF (13/16 Pages) Catalyst Semiconductor – High Frequency 100mA CMOS Charge Pump, Inverter/Doubler

CAT661
Cascade Operation for Higher Negative Voltages
The CAT661 can be cascaded as shown in Figure 28 to generate more negative voltage levels. The output resistance is
approximately the sum of the individual CAT661 output resistance.
V_OUT = −N x V_IN, where N represents the number of cascaded devices.
+
C1
+V_IN
8
8
2
CAT661
3
“1”
2
+
3
CAT661
“N”
C1N
4
5
4
5
V_OUT = −NV_IN
C2
+
C2
+
Figure 28. Cascading to Increase Output Voltage
Parallel Operation
Paralleling CAT661 devices will lower output resistance. As shown in Figure 29, each device requires its own pump
capacitor, C2, but the output reservoir capacitor is shared with all devices. The value of C2 should be increased by a factor of
N, where N is the number of devices.
ROUT
+
N
ROUT (of CAT661)
(NUMBER OF DEVICES)
+
C1
+V_IN
8
8
2
CAT661
3
“1”
2
+
3
CAT661
“N”
C1N
4
5
4
5
C2
+
Figure 29. Reduce Output Resistance BY Paralleling Devices
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